Preheat oven to 375 degrees F. Toss cauliflower in 3-4 tablespoons of oil; arrange in a single layer on a baking sheet, and liberally salt and pepper. Roast until evenly browned (20-30 minutes).

In a small stock pot, melt butter over medium heat. Add onion, carrots, celery and potato; saute until onions are translucent and potatoes are beginning to soften. Do NOT allow the mixture to brown. Add the flour; stir until a roux (a thick paste) forms. Add the vegetable stock and bay leaf. Bring to a boil, and immediately reduce to a simmer. Stir occasionally until thickened; remove from heat.

Remove bay leaf. If you have an immersion blender, you can add the roasted cauliflower to the pot, and puree until the soup reaches the desired consistency. If you're using a food processor, puree 1-2 cups of thickened stock and 1/2 cup of cauliflower at a time. For a really smooth final product, you can pass the pureed soup through a mesh sieve or china cap - but I like mine a little chunky!

Return to pan; swirl in cream and season with salt and pepper, to taste. Garnish with chili pepper, if desired. Enjoy!